In 1940, the Nazis set a secret project in motion, Operation Bernhard. Chosen from the rows of men on their way to the gas chambers were typographers and printers. The 142 men selected were transferred to the strictly isolated block 19 in Sachsenhausen concentration camp. The prisoners were presented with an enormous task: producing counterfeit British bank notes to the value of hundreds of millions of pounds.

The notes, considered some of the most perfect counterfeits ever produced, were to be dropped from planes over London, with the aim of destabilising the British economy. One of the typographers was a young Jewish boy from Oslo, Moritz Nachtstern. Here he shares his shocking tale, from his arrest in Oslo, the journey to Germany, the horrors of the camp, to the impossibility of the operation: they had to produce exquisite forgeries, but as slowly as they could, to frustrate Nazi plans and to maintain their own safety.